U.S. patent number 5,351,772 [Application Number 08/016,085] was granted by the patent office on 1994-10-04 for polycrystalline diamond cutting element.
This patent grant is currently assigned to Baker Hughes, Incorporated. Invention is credited to Redd H. Smith.
United States Patent |
5,351,772 |
Smith |
October 4, 1994 |
Polycrystalline diamond cutting element
Abstract
A substantially polycrystalline diamond compact cutting element
for drilling subterranean formations. The cutting element includes
a cemented carbide substrate having radially extending raised lands
on one side thereof, to and over which is formed and bonded a
polycrystalline diamond table.
Inventors: |
Smith; Redd H. (Salt Lake City,
UT) |
Assignee: |
Baker Hughes, Incorporated
(Houston, TX)
|
Family
ID: |
21775319 |
Appl.
No.: |
08/016,085 |
Filed: |
February 10, 1993 |
Current U.S.
Class: |
175/428; 175/432;
51/293 |
Current CPC
Class: |
E21B
10/5735 (20130101) |
Current International
Class: |
E21B
10/56 (20060101); E21B 10/46 (20060101); E21B
010/46 () |
Field of
Search: |
;175/426,428,430,432,433,444 ;76/108.2 ;407/118,119
;51/293,295 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Bagnell; David J.
Attorney, Agent or Firm: Trask, Britt & Rossa
Claims
What is claimed is:
1. A cutting element for use on a rotary drag bit for drilling
subterranean formations, said cutting element comprising:
a substrate having at least one substantially planar side and an
arcuate perimeter comprising at least a segment of a circle, and
further including a plurality of upwardly-projecting lands located
on said at least one substantially planar side adjacent the
perimeter of said substrate, said lands extending radially inwardly
from said arcuate perimeter toward the location of the center of
said circular segment; and
a table comprising polycrystalline superhard material bonded to
said substrate on said at least one substantially planar side
thereof, extending between said lands and having a depth greater
than the height of said upwardly-projecting lands.
2. The cutting element of claim 1, wherein said superhard material
table comprises a polycrystalline diamond compact.
3. The cutting element of claim 2, wherein said polycrystalline
diamond compact comprises a thermally stable product.
4. The cutting element of claim 1, wherein said lands are
substantially evenly spaced about said perimeter of said
substrate.
5. The cutting element of claim 1, wherein said substrate includes
said center location, and said lands extend radially inwardly from
said perimeter thereto.
6. The cutting element of claim 5, wherein said perimeter comprises
a half-circle.
7. The cutting element of claim 5, wherein said perimeter comprises
a circle.
8. The cutting element of claim 5, wherein said lands are spaced
radially inwardly from said substrate perimeter.
9. The cutting element of claim 5, wherein said lands abut said
substrate perimeter.
10. The cutting element of claim 1, wherein said lands are spaced
radially inwardly from said substrate perimeter.
11. The cutting element of claim 1, wherein said lands abut said
substrate perimeter.
12. The cutting element of claim 1, wherein at least some of said
lands decrease in height as they increase in distance from said
substrate perimeter.
13. The cutting element of claim 1, wherein at least some of said
lands increase in height as they increase in distance from said
substrate perimeter.
14. The cutting element of claim 1, wherein said lands decrease in
width as they increase in distance from said substrate
perimeter.
15. The cutting element of claim 1, wherein said lands increase in
width as they increase in distance from said perimeter.
16. The cutting element of claim 1, wherein said lands vary in
cross-sectional configuration between said perimeter and said
center of said substrate.
17. The cutting element of claim 1, wherein at least some of said
lands comprise discontinuous sub-lands.
18. The cutting element of claim 1, wherein said lands are of
rectangular cross section.
19. The cutting element of claim 1, wherein said lands are of
arcuate cross section.
20. The cutting element of claim 1, wherein said lands abut said
substrate perimeter.
21. The cutting element of claim 1, wherein said lands are spaced
inwardly from said substrate perimeter.
22. A cutting element for use on a rotary drag bit for drilling
subterranean formations, said cutting element comprising:
a substrate having at least one substantially planar side and a
perimeter, and further including a plurality of upwardly-projecting
lands located on said at least one substantially planar side
adjacent the perimeter of said substrate wherein said lands meet
proximate the center of said substrate; and
a table comprising polycrystalline superhard material bonded to
said substrate on said at least one substantially planar side
thereof, extending between said lands and having a depth greater
than the height of said upwardly-projecting lands.
23. A cutting element for use on a rotary drag bit for drilling
subterranean formations, said cutting element comprising:
a substrate having at least one substantially planar side and a
perimeter, and further including a plurality of upwardly-projecting
lands located on said at least one substantially planar side
adjacent the perimeter of said substrate wherein said substantially
planar substrate side is convex; and
a table comprising polycrystalline superhard material bonded to
said substrate on said at least one substantially planar side
thereof, extending between said lands and having a depth greater
than the height of said upwardly-projecting lands.
24. A cutting element for use on a rotary drag bit for drilling
subterranean formations, said cutting element comprising:
a substrate having at least one substantially planar side and a
perimeter, and further including a plurality of upwardly-projecting
lands located on said at least one substantially planar side
adjacent the perimeter of said substrate wherein said substantially
planar substrate side is concave; and
a table comprising polycrystalline superhard material bonded to
said substrate on said at least one substantially planar side
thereof, extending between said lands and having a depth greater
than the height of said upwardly-projecting lands.
Description
BACKGROUND
1. Field of the Invention
The present invention relates generally to superhard cutting
elements, and more specifically to substantially planar
polycrystalline diamond compact cutting elements comprising a
polycrystalline diamond table formed and bonded to a supporting
substrate during formation of the cutting element.
2State of the Art
Polycrystalline diamond compact cutting elements, commonly known as
PDC's, have been commercially available for over twenty years.
PDC's may be self-supporting, or may comprise a substantially
planar diamond table bonded during formation to a supporting
substrate. The diamond table/substrate cutting element structure is
formed by stacking in a receptacle layers of fine diamond crystals
(100 microns or less) and metal catalyst powder, alternating with
wafer-like metal substrates of cemented carbide. In some cases, the
catalyst o material may be incorporated in the substrate in
addition to or in lieu of using a powdered catalyst intermixed with
the diamond crystals. The loaded receptacle is subsequently placed
in an ultrahigh temperature (typically 1450.degree.-1600.degree.
C.), ultrahigh pressure (typically 50-70 kilobar) diamond press
wherein the diamond crystals, stimulated by the catalytic effect of
the metal powder, bond to each other and to the substrate material.
The spaces in the diamond table between the diamond to diamond
bonds are filled with residual metal catalyst. A so-called
thermally stable PDC product (commonly termed a TSP) may be formed
by leaching out the metal in the diamond table. Alternatively,
silicon, which possesses a coefficient of thermal expansion similar
to that of diamond, may be used to bond diamond particles to
produce a Si-bonded TSP. TSP's are capable of enduring higher
temperatures (on the order of 1200.degree. C.) without degradation,
in comparison to normal PDC's, which experience thermal degradation
upon exposure to temperatures of about 750.degree.-800.degree.
C.
While PDC and TSP cutting elements employed in rotary drag bits for
earth boring have achieved major advances in obtainable rate of
penetration and in greatly expanding the types of formations
suitable for drilling with diamond bits at economically viable
cost, the diamond table/substrate configuration of state of the art
planar cutting elements leave something to be desired.
First, the interface of the diamond table with the substrate
(typically tungsten carbide, or WC) is subject to high residual
shear stresses arising from formation of the cutting element, as
after cooling the differing coefficients of thermal expansion of
the diamond and substrate material result in thermally-induced
stresses. In addition, finite element analysis (FEA) has
demonstrated that high tensile stresses exist in a localized region
in the outer cylindrical substrate surface and internally in the WC
substrate. Both of these phenomena are deleterious to the life of
the cutting element during drilling operations, as the stresses,
when augmented by stresses attributable to the loading of the
cutting element by the formation, may cause spalling, fracture or
even delamination of the diamond table from the substrate.
In addition to the foregoing shortcomings, state of the art PDC's
often lack sufficient diamond volume to cut highly abrasive
formations, as the thickness of the diamond table is limited due to
the inability of a relatively thick diamond table to adequately
bond to the substrate.
Finally, the benefits of a multi-thickness diamond table, which
produces a kerfing action during drilling as the thickness
portions, have been recognized. However, all such prior art PDC
configurations (see, for example, U.S. Pat. Nos. 4,784,023 and
5,120,327) employ parallel linear interleaved ridges of diamond and
substrate extending across the cutting element. Such a
configuration, which is purported by the patentee to alleviate the
diamond table/substrate interface stresses, may actually by its
asymmetrical nature, aggravate rather than alleviate and
undesirably concentrate such stresses, as well as substrate outer
surface stresses. In fact, the embodiment of the '327 patent,
wherein a circumferential ring of diamond is formed around the
substrate ridges to resist crack formation and propagation in the
substrate, is a tacit admission of the basic parallel ridge
structure's inability to remedy the basic interface stress
problem.
Another PDC cutting element structure which affords a
multiple-depth diamond table is disclosed in European Patent
Specification Publication No. 0 322 214 B1. This structure's
substrate ridges resemble a "bull's eye" pattern in one embodiment,
and a spiral pattern in another. While allegedly providing curved
cutting ridges as the cutting element wears, wear of such ridges
causes the primary contact points between the cutting element and
the formation to migrate rapidly laterally, so that a deep kerf or
cleft in the formation at a substantially constant radial location
is never effected.
SUMMARY OF THE INVENTION
In contrast to the prior art, the cutting element of the present
invention comprises a substantially planar structure of circular
cross section comprising a PDC diamond table bonded to a WC
substrate having lands thereon spaced about the perimeter of the
substrate. The diamond table depth exceeds the height of the
substrate lands so that an all-diamond cutting surface is
presented.
In a preferred embodiment, the substrate lands are substantially
symmetrically spaced and extend radially from a position proximate
to the center of the substrate toward the perimeter. The lands may
or may not extend to the very center of the substrate, and may or
may not reach the outer edge of the substrate. The lands may
increase in height from the center of the substrate to the
periphery, decrease in height, or increase and then decrease in
height, or vice versa. Similarly, the lands may increase or
decrease in width as they extend from the substrate center to the
periphery. The lands may be of square, rectangular, triangular,
arcuate, or other suitable cross-section. The substrate interface
surface itself (aside from the lands) may be convex or concave. The
lands may be linear, or arcuate. More than one of the foregoing
features may be combined in a single structure.
The radial land configuration at the diamond table/substrate
interface is believed to redistribute the interface stresses,
reduce their areas of concentration, as well as reducing outer
surface stresses in the substrate by correlating the radially
symmetric stress fields and radially symmetric substrate lands and
interposed diamond material. Stated another way, the radial land
configuration of the present invention provides the ability to
redistribute the stress field in a more favorable way. FEA
demonstrates that the continuous circumferential tensile stress
field normally present around the periphery of a PDC substrate is
modified in all three dimensions and the stress field continuity
interrupted when the present invention is employed, which
phenomenon tends to prevent cracks originating on the periphery of
the substrate from propagating across the field and delaminating
the diamond table. Moreover, FEA demonstrates that the present
invention also separates the discontinuous tensile stress
concentration with areas of high compressive stress, the latter
serving as crack arrestors. The lands enhance the diamond
table/substrate bond by increasing surface area and resistance to
impact and shear forces, and the increased diamond volume provided
by the deeper diamond table provides enhanced wear characteristics
for cutting highly abrasive formations. The lands permit and in
fact promote the use of a thicker diamond table with reduced risk
of spalling or fracture of the table. Similarly, the
multi-thickness diamond table produced by the diamond extending
between the lands provides a kerfing action against the formation
being drilled as the cutting element wears.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A, 1B and 1C are, respectively, a top elevation of a
substrate employed in a first embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 2A, 2B and 2C are, respectively, a top elevation of a
substrate employed in a second embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 3A, 3B and 3C are, respectively, a top elevation of a
substrate employed in a third embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 4A, 4B and 4C are, respectively, a top elevation of a
substrate employed in a fourth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 5A, 5B and 5C are, respectively, a top elevation of a
substrate employed in a fifth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 6A, 6B and 6C are, respectively, a top elevation of a
substrate employed in a sixth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 7A, 7B and 7C are, respectively, a top elevation of a
substrate employed in a seventh embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 8A, 8B and 8C are, respectively, a top elevation of a
substrate employed in an eighth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 9A, 9B and 9C are, respectively, a top elevation of a
substrate employed in a ninth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 10A, 10B and 10C are, respectively, a top elevation of a
substrate employed in a tenth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 11A, 11B and 11C are, respectively, a top elevation of a
substrate employed in an eleventh embodiment of a PDC cutting
element according to the present invention, a side view of that
cutting element embodiment, and a perspective view of another
example of that cutting element embodiment employing a thicker
substrate;
FIGS. 12A, 12B and 12C are, respectively, a top elevation of a
substrate employed in a twelfth embodiment of a PDC cutting element
according to the present invention, a side view of that cutting
element embodiment, and a perspective view of another example of
that cutting element embodiment employing a thicker substrate;
FIGS. 13A, 13B and 13C are, respectively, a top elevation of a
substrate employed in a thirteenth embodiment of a PDC cutting
element according to the present invention, a side view of that
cutting element embodiment, and a perspective view of another
example of that cutting element embodiment employing a thicker
substrate; and
FIG. 14 is a perspective view of a partially worn cutting element
according to the present invention shown mounted on the face of a
drill bit.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
Referring FIGS. 1A-1C of the drawings, a first embodiment of the
cutting element 10 of the present invention is depicted. FIG. 1A
shows, looking down from above, a rounded cemented carbide
substrate 12 having a substantially planar surface 14 on which a
plurality of lands 16 are spaced in abutting relationship to the
periphery 18 of substrate 12. FIG. 1B depicts a cutting element 10
with PDC diamond table 20 formed on and bonded to substrate 12,
lands 16 projecting upwardly into diamond table 20 and diamond
table 20 extending downwardly into channels 22 between lands 16.
Lands 16 in this embodiment of the invention are of square or
rectangular cross section and are substantially equal in size and
substantially equally spaced above the periphery 18 of substrate
12. As depicted in FIG. 1C, however, lands may be of unequal height
and width, and alternate in such characteristics. It should finally
be noted that lands 16 are relatively short or truncated in their
radial dimension, and extend only a short distance toward the
center 24 of substrate 12. As also shown in FIGS. 1B and 1C, the
thickness of substrate 12 may vary greatly and does not affect the
invention. The cutting surface 26 of diamond table 20 is depicted
in FIGS. 1B and 1C as planar with a sharp edge or corner 28, but it
should be recognized that chamfered or rounded edges are also
contemplated as being a feature of cutting elements of the present
invention. Diamond table 20 is shown to be of exaggerated
thickness, for clarity, in all of the drawing figures.
FIGS. 2-13 depict additional embodiments of the present invention,
and features therein corresponding to those of FIGS. 1A-1C will be
identified with like reference numerals for the sake of
clarity.
The cutting element embodiment 110 of FIGS. 2A-2C employs a
plurality of elongated lands 16 extending radially from the
periphery 18 of a substrate 12, and its planar surface comprises a
plurality of separated, wedge-shaped behind channels 22. As with
the first embodiment, lands 16 abut periphery 18 but unlike the
first embodiment, extend inwardly to form a solid core land 116 at
their juncture. As with the embodiment of FIGS. 1A-1C, the lands 16
may be of various heights and widths.
FIGS. 3A-3C depict a third embodiment 210 of the cutting element of
the present invention, wherein elongated lands 16 extend radially
from an area near the center 24 of substrate 12 to the periphery
thereof, channels 22 being open to the center 24. Lands 16 may be
of uniform height and width, or vary. Lands 16 may also have top
surfaces 216 parallel to substrate surface 14, or surfaces 216 may
slope toward or away from center 24, or alternate in their slope as
depicted in FIG. 3B.
FIGS. 4A-4C depict a fourth embodiment 310 of the cutting element
of the invention, cutting element 310 having elongated lands 16
joined at the center 24 of substrate 12 but removed from the
periphery 18, blind channels 22 all communicating with substrate
surface 14 in peripheral zone 314. As shown in broken lines, some
lands 16 may extend to the periphery 18 of substrate 12 while
alternating lands 16 are removed therefrom. As is clearly
illustrated in FIG. 4B, land 16 may have a half-circular or other
arcuately-bounded cross section. As with the previously described
embodiments, lands 16 may vary in height, width and slope, and may
be of rectangular cross section instead of arcuate.
FIGS. 5A-5C depict a cutting element embodiment 410 which is
similar to that of FIGS. 3A-3C except that lands 16 extend neither
to the center 24 nor the periphery of substrate 12. As depicted in
FIG. 5B, the heights of alternating lands may vary, as may the
width, slope, cross-sectional configuration and length.
FIGS. 6A-6C depict a cutting element 510 which may be generally
described as a combination of the embodiment of FIGS. 3 with that
of FIGS. 4. Two sets of interleaved lands 16 are employed, one set
abutting the periphery 18 of substrate 12, and extending radially
inwardly therefrom, and the other emanating radially from the
center 24 but terminating short of periphery 18. The lands may vary
in width, height, slope and cross section, and one set of lands may
have one common set of characteristics, such as height, while the
other set may differ in that same characteristic (see FIG. 6B).
FIGS. 7A-7C depict yet another embodiment 610 of the cutting
element of the invention, lands 16 in this embodiment are of
triangular cross section and increase in height from the center 24
of substrate 12 to the periphery 18 thereof.
FIGS. 8A-8C depict a cutting element 710 wherein the substrate 12
has a convex surface 614 to which diamond table 20 is formed, and
lands 16, of arcuate cross section extend from center 24 to
periphery 18 of substrate 12. It should also be noted that diamond
table 20 is itself arcuate, or convex, in configuration, following
the contour of substrate surface 614.
FIGS. 9A-9C show another cutting element configuration 810 wherein
lands 16, of triangular cross section, decrease in height from
center 24 to periphery 18 of substrate 12.
FIGS. 10A-10C show a cutting element 910 having spiral-landed
substrate 12, wherein each land 16 extends from the center 24 of
substrate 12 in an arcuate path to the perimeter 18. As
illustrated, the lands 16 are of uniform height, width, length and
cross-sectional configuration, but such characteristics may in fact
be varied.
FIGS. 11A-11C depict yet another embodiment 1010 at the present
invention, cutting element 1010 having lands 16 which increase and
then decrease in height as they extend radially from proximate to
the center 24 to the periphery 18 of substrate 12.
FIGS. 12A-12C show a cutting element embodiment 1110 having a
substrate 12 with a concave surface 1114 to which diamond table 20
is formed, lands 16 extending from the periphery 18 to the center
24 of substrate 12 with a constant level upper surface and thereby
a steadily increasing height as the center 24 of substrate 12 is
approached. As shown in FIG. 12B, the cutting element 26 of the
diamond table 20 may be flat, or may comprise a concave surface
26.
FIGS. 13A-13C show a cutting element embodiment 1210 having a
substrate 12 having lands 16 which are comprised of radially
discontinuous sub-lands 1216. It is also contemplated that each set
of sub-lands 1216 lying on the same radius may be rotationally
offset from the adjacent set.
FIG. 14 depicts the embodiment 110 of FIGS. 2A-2C mounted on the
face 1202 of drill bit 1200, and illustrates the kerfing or
scribing structure 1204 achieved by the inter-land increased
diamond table thickness in channels 22 of the present invention as
the cutting element wears. While the cutting element 110 has been
shown in FIG. 14 mounted directly to the bit face 1202 and
buttressed by matrix material 1206, it will be understood that it
may or any of the other embodiments may be secured to a stud or
other carrier element known in the art, the cutting structure there
being secured to the bit face via the carrier element.
It should further be noted that, in contrast to the kerfing type
cutting elements of the prior art, the cutting elements of the
present invention need not be rotationally oriented to a specific
position prior to affixation to a carrier structure or directly to
the face of the drill bit, as shown in FIG. 14. The prior art
cutting elements, with their parallel lands extending across the
substrate must be specifically oriented so that the lands are
generally perpendicular to the bit face to achieve a kerfing
effect. Moreover, the non-radial orientation of the prior art lands
is believed to aggravate the stress concentrations associated with
the substrate/diamond table interface, resulting in a less robust,
less impact-resistant structure than the present invention.
It will be appreciated by one of ordinary skill in the art that one
or more features of the illustrated embodiments may be combined
with one or more features from another to form yet another
combination within the scope of the invention as described and
claimed herein. Further, while the substrate structures have been
illustrated and described as being uniform or symmetrical as to
features of the lands and the substrate surface, the invention is
not so limited. Moreover, the features of the present invention may
be employed in half-round, quarter-round, or even "tombstone"
shaped cutting elements to great advantage, and the shape of the
cutting surface and the configuration of the cutting surface edge
or edges of the diamond table may be varied as desired without
diminishing the advantages or utility of the invention. Finally, it
is contemplated that the invention may be applicable to cutting
elements having polycrystalline cubic boron nitride cutting
tables.
* * * * *